The present invention relates to a pointing device used on a personal computer, etc., and more particularly to a pointing device with a cleaning alarm, which warns that cleaning becomes necessary due to excessive contamination.
A mouse is a typical pointing device being used on a personal computer or a work station. There are two types of mice, optical mouse and mechanical mouse, the latter being widely used at present. As is well known in the art, a mechanical mouse is slid on a desk surface to rotate a ball at its bottom whose rotation is conveyed to two rollers. Rotation of each roller is detected by an encoder to calculate the amount of movement of the mouse. On a display screen, a pointer moves according to the result of the calculation. The use of such a mechanical mouse over a long period of time causes dust or dirt to be adhered to the surfaces of the ball and rollers, which may prevent the pointer from precisely following and may cause a failure of the mouse. Although such problems could be avoided by disassembling the mouse and cleaning movable portions such as ball and rollers at regular intervals, many users continue to use mice without disassembling and cleaning the mice because such actions are troublesome. To solve this problem, it has been proposed that a mouse is provided with a cleaning mechanism.
For example, Japanese Published Unexamined Patent Application (PUPA) No. 62-135927 discloses a pointing device having cleaning members for removing dust contacted and adhered to a ball and encoder rollers, respectively. Both members are made of materials which do not hinder the smooth rotation of the ball and rollers, and remove dust or dirt adhered to the surfaces of the ball and rollers as they rotate.
Although it is prefer table, in principle, to clean both the ball and rollers, there are so me suggestions to clean either one of them. For example, Japanese PUP A No. 1-94422 discloses a pointing device in which a member for cleaning the surface of a ball is detachably mounted at a ball supporting section, and Japanese Published Examined Utility Model Application No. 2-77741 discloses a mouse provided with a brush which contacts a driver rotating according to the rotation of a ball.
For such integrated c leaning mechanisms, it is necessary to minimize the influence on the rotation of the ball and rollers (especially, the rollers are subject to failure when load increases), which results in limited cleaning capability so that dust or dirt adhered to their surfaces cannot be completely removed. Further, there is a problem how to dispose the removed dust. Therefore, in respect of the complete cleaning of the mouse, disassembling and cleaning by the user are most preferable. The problem is when and how the user is to be prompted to clean.